An example of a prior art device for removing debris from a liquid passed through a flume is disclosed in DE 42 13 847 A1. As in most of the prior art, a significant structural connection exists between the separator and the conveyor, the conveyor screw having a double function. The conveyor screw, as a part of the separator, serves to remove the screened materials from, and to clean, the separation area. On the other hand the conveyor screw, as a part of the conveyor, fulfills a transfer function. With respect to the art, in which the conveyor screw is only part of the conveyor, there exists a spatial relationship between the separator and the conveyor wherein the discharge point for the filtered material collected on the separation area and the intake chute of the conveyor overlap at least partially in vertical projection. In addition, the conveyor housing is connected in fixed manner with parts of the separator and serves to support a common drive for both the separator and the conveyor. In one embodiment, the axis of the separator is positioned parallel to and at a distance from the axis of the conveyor, the axis of the conveyor being positioned below the axis of the separator. However in this embodiment the device is still equipped with a common drive for both the separator and the conveyor, making gearing necessary for power distribution and for different rates of revolution and/or for different directions of rotation. In addition, in this version of the prior art there exists a physical or structural relationship between the separator and the conveyor, for example elements of the separator are supported on the housing of the conveyor.
From DE 91 13 761 U1 it is known to position the rotating axes of the conveyor screw on the one hand, and of the separator on the other hand, at a distance with respect to each other, especially parallel to one another, and preferably orientated one about the other. Here again there is still a common drive and distribution gearing for the conveyor screw of the conveyor and for the separation area of the separator in form of a perforated grate or filter.
DE 36 30 755 C2 shows a device having a separation area in the form of a grid composed of a plurality of grating bars and driven in rotation. The liquid enters the separation area through an open face defined therein and flows therethrough in the liquid flow direction within the flume. The material to be screened is deposited on the inner surface of the cylindrical separation area and is moved upwardly by the rotation of the separation area. A stripper is provided as a removal device to remove the deposited material from the separation area, the stripper extending at least partially into the gaps between the grating bars. A conveyor is positioned coaxially with the axis or the separator. The conveyor, a screw conveyor device, removes the material deposited on the separation area and conveys the screened material in the direction of the liquid flow in the flume at an upwardly inclined angle with respect to, and out of the flume. The material is discharged at a discharge collection point. The cylindrical separation area of this device is supported on the housing of the conveyor. The separation area of the separator and the conveyor are thus a common unit. This unit is mounted in the flume in an inclined manner, where the angle of the common axis of the separator and conveyor with respect to a horizontal plane may be varied within limits. Depending on the installation conditions it is necessary to construct the separation area and the conveyor with respect to each other, and to then manufacture, deliver and install both the separator and conveyor as a single unit. Different devices must be manufactured depending on the different width of the flumes, discharge height, and so on.
A similar device is disclosed in DE 34 20 157 C1. Here the separation area, for example a sieve, or grating, and the conveyor are a single structural unit having a coaxial arrangement of their axes with one another. The separation area is connected to the shaft of the screw conveyor device, and is indirectly driven through this connection making only one motor necessary for driving both the separation area and the conveyor screw.
The prior art devices for the removal of material to be screened out of a liquid flowing in a flume are equipped with a separation area which is either located in a fixed position or driven in rotation. A fixed separation area should not be designed cylindrically nor to continuously extending around the circumference the separation area, but may be provided with a sectional gap thereof positioned in the region above to the liquid level in the flume. However, aside from these devices, the direction of development in this field of devices is directed to the fact that the separator, inclosing a separation area, on the one hand, and the conveyor, on the other hand, always form a single or common unit, in which there is not only a spatial relationship of the parts to one another, but there is also a functional and structural connection of these parts to each other. This is especially the case where the shaft or the separator is coaxial with shaft or the conveyor screw. In addition, the conveyor is always located in the flume so that it conveys the screened and removed material in the flow direction of the liquid inclined upwardly, with respect to the flume, up to a discharge point. Advantageously, the open inflow face of the cylindrical separation area here is obstructed to a minimal extent by the conveyor. A large portion of the conveyor housing in which an intake chute is defined for receiving the material to be discharged from the separator is located above the liquid level of the flume. The disadvantage of the prior art devices consists of the fact that for each installation, in which the device is used, these units must be separately manufactured. Even for flumes of the same width but different positioning angles and the same depositing height the overall length of the device must be varied.